Kent's highend audio universe

Weiss OP1-BP

Discrete OP1-BP – a truly transparent, discrete operational amplifier module.


Superb noise performance:

  • 1nV/√Hz voltage noise density (1kHz)
  • 30nVpp voltage noise (0.1-10Hz)
  • 0.7pA/√Hz current noise density (1kHz)
  • 80pApp current noise (0.1-10Hz)
  • no common-mode current noise from bias cancellation

Outstanding distortion specifications:

  • THD+N -152dB (+20dBu, 1kHz, 22kHz BW, 600Ω)
  • THD+N -148dB (+20dBu, 10kHz, 80kHz BW, 600Ω)
  • distortion spectrum consists almost entirely of 2nd and 3rd harmonic
  • no significant crossover distortion, even with 200Ω load
  • no significant common mode distortion, even with very high source impedances

Impressive AC performance:

  • 50V/µs slew rte, highly symmetrical
  • 95MHz gain bandwidth product
  • 700kHz power bandwidth (20Vpp into 600Ω)
  • 300kHz power bandwidth (20Vpp into 200Ω)

Superior DC precision:

  • offset 10µV
  • input bias current +-60nA
  • input offset current +-10nA

Excellent load driving capability:

  • 27Vpp(+21.8dBu) in 200Ω (+-15V supply)
  • 20Vpp(+19.2dBu) in 100Ω (+-15V supply)
  • 10Vpp(+13.2dBu) in 50Ω (+-15V supply)
  • adjustable class A output current, factory trimmed to 30mA
  • very low output impedance
  • extensive short-circuit protection

Salient insensitivity to power supply deficiencies:

  • very high PSRR with little degradtion towards high frequencies
  • individual RC decoupling of amplifier sub-circuits eliminates the interaction of the various amplifier stages and makes the amplifier insensitive to power supply inductance
  • high performance on-board decoupling capacitors, 2.4µF total
  • no need for additional external decoupling capacitors
  • recommended power supply range from +-5V to +-18V

Carefully thermal design:

  • excellent stability of any bias condition
  • full thermal isolation of the sensitive input stage from the power output stage
  • fast settling of bias conditions after start up


  • 42 x 28 x 17mm (1.65 x 1.1 x 0.67 inches)
  • API2520 standard pinout

  1. Ackcheng

    21 January

    Very impressive data Kent!

    But why 8 of them? Is it a 8 channels DAC?

  2. admin

    21 January

    It knocks me out………(cut thousands of words about what should be a perfect gain/amp stage).

    It is a stereo DAC, each channel has full balanced + and – phases signal path.

    Left+/Left- & Right+/Right- This requires 4 amp modules.

    In Medea+, OP1-BP works for 2 different roles:

    1) I/V conversion
    2) Output driver

    Both (1) and (2) are taken care by 4 OP1-BP individually. Therefore there are total of 8 modules. I can tell you these really are the best one can find.

    We discussed ESS9018 uses multi channels summing for better stereo performances. This leads to a much higher demand and critical on the analogue section. I have to say it once again Daniel Weiss and Samuel Groner are genius!

  3. ackcheng

    21 January

    Looking at the impressive measurement data. This is definitely the best module on earth!

  4. cowonice

    21 January

    Too expensive to afford yet still feel happy and exciting to see the progress of improving digital playback. So the very rich audiophiles will be using digital DACs much more expensive than what the top studio guys use, right? BTW, it will be really exciting to have a head-to-head of Medea Plus Vs DAC202 or DCS or EMM Lab!

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